Tractor.



U. PAVESI & G. TOL'OTTI.

w meme. APPLICATI ON FILED OCT. 29; l9l5.

Patented Apr. 1,1919.-

2 SHEETS-SHEET I.

u. PAVESI & a. mom.

TRACTOR.

APPLICATION FILED 001329. I915.

' Patented Apr. 1,1919. 7

2 SHEETSSHEET 2- o Pal/e51 ilt/b75100? woo rnvnsr AND GIULIO TOLOTTI, or MILAN, ITALY,

ASSIGNORS, BY MESNE ASSIGN- MENTS, TO THE P. T. WHEEL COMPANY, OF DAYTON, OHIO, A CORPORATION OF OHIO.

TRACTOR.

To all whom it may concern Beit known that we, Uoo Pnvnsr and Ginnio TOLOTTI, both subjects of the King of Italy, the post-office address of both being 18 Oglio street, Milan, Italy. have invented new and useful Improvements in Tractors, of which the following is a specification.

This invention relates to a tractor such as employed for drawing very heavy loads where it is necessary have a very good tractive effect upon the ground. It has been attempted heretofore to produce such a wheel by attaching to the wheel rim a plurality of shoes which engage the ground as the wheel rotates. and these shoes have usually been provided with means for digging into the ground to give a purchase'or reaction point upon which the wheel can exert its tractive effort.

A principal object of the invention is to produce a tractor which will give substantially the same effect as though the wheel were rolling upon a track. I

Another object'of the present invention is to produce a tractor having bearing members supported by a. wheel in such a way that as the wheel advances it places the bear ing members in succession upon the ground and then rolls across each bearing member in succession.

A further object of the invention is to provide 'means for preventing the wheel from slipping on each bearing member as it rolls across it.

A further object of the invention is to provide a tractor-wheel carrying bearing members or shoes and having improved 'erates as a gear rolling upon the rack.

means for supporting and guidlng tligbearing members upon the wheel so that when the wheel advances, it will maintaln at least two of these bearing members upon the ground and the bearing members will then operate to support the wheel which rolls.

across their upper side with a true rolling movement. and also to construct the bearing members so that in the rolling movement the wheel makes a-mechanical engagement with them so that thefbearing members constitute sections 0 a rack and the wheel op- Thus the wheel rolls uniformly and exerts a continuous uniform tractive effort.

Fi-irther objects of the invention will appear more fully hereinafter.

Specification of Letters Patent.

that the wheel shall Patented Apr. 1, 1919.

Application filed October 29, 1915. Serial No. seine.

The invention consists in the general combination of parts and features to be described hereafter all of which contribute to produce an efficient tractor.

A preferred embodiment of the invention is described in the following specification, while the broad scope of the invention is pointedout in the appended claims.

In the drawing v Figure 1 is a side elevation and partial section of a tractor embodying our invention. Fig. 2 is a vertical section taken through the lower portion of the tractor shown in Fig. 1 but showing a singlebearing member in place so as to render the view more intelligible.

Fig. 3 is a diagrammatic side elevation illustrating another embodiment of the in' shoes. 4

The tractor preferably comprises a wheel 1 which may be of spider form. Upon this wheel we mount a plurality of bearing mem bers which are disposed along the rim of the wheel and we provide means for supporting and guiding the bearing members on the wheel so that when the wheel advances it operates to laythe bearing members in succession upon the ground. The rim of the wheel is supported upon each bearing member in succession and moves forward by a rolling movement on each bearing member. The bearing members are preferably bodily movable in and out in a radial direction on the wheel, and the tractor operates in such a way that there are constantly tWo of the bearing members on the ground under the wheel'and across which the wheel rolls. As

soon as the wheel is supported on the fore most bearing member, which is on the round the rear bearin member is released and is preferably arranged to be pulled inardly 0n the wheel. In this Way' We get substantially the same effect as though the wheel were rolling along on a continuous track made up of members such aS the bearing members.

. In order to prevent any slipping under the rim of the wheel where it rolls upon the bearing members, and in this way to give a very effective and high tractive effort, we prebearing members 3 which are supportedon the wheel so as to be bodily movable on the rim and as the wheel rotates it lays these members in succession upon the ground, indicated by the line 4. The mechanical engaging means between the bearing members and the wheel is preferably constructed on a mechanical theory of construction. for a rack and pinion or' gear wheel. That is, we prefer to employ involute or cycloidal curves along which the engagement of the wheel and the bearing members occurs. This enables the wheel to exert a uniform tractive effort. According to our invention the mechanical construction may take a variety; of forms to get the effect described above. By way of example, in Fig. 1, the bearing members 3 are mounted in the spaces between guide members or studs 5 which are placed equidistant along the rim of the wheel and which rigidly connect the rim members 2. Each bearing member 3 is preferably in the form of a shell-like block having a platelike body 6, the forward and rear ends of which present shoulders 7 adapted to engage the ground and give a good holdor purchase upon it. In this embodiment of the invention, each bearing member substantially constitutes a single gear tooth of a rack which would cooperate mechanically with the studs 5 to transmit power to or from the wheel 1. The forward wall of each bearing member, that is, the wall which is disposed on the side toward which the wheel is moving, is provided with a curved profile or curved face 8 which curve. is substantially an involute or cycloidal curve designed to cooperate withthe stud so that it will maintain itself in engagement with the stud as the wheel rolls along overthe bearing member. A similarly curved rear face 9 is formed on each bearing member which maintains contact with each stud 5 as it moves upwardly and away from the ground toward the rear side of the wheel. It should be noted that in the embodiment shown in Fig. 1 there is no ivotal orsimilar connection which attaches the bearing members to the wheel. Their connection to the wheel may be described-as a floating connection and they are preferably simply atthat they swing tached by springs 10 which pull them in or shoe is preferably formed with central I and side webs 11 which connect the forward and rear walls of the bearing members and these side webs 11 preferably lie against and are guided by the inner faces of the rim members 2.

When the wheel is operating the rim members 2 roll on the upper sides of the plate portion 6 of the bearing members on substantially fiat faces 12 (see Fig. 2) at which points the plateprojects ,so as" to give the effect of a flange at each side under the rim which supports the wheel independently of the mechanical engaging means. The studs 5 codperating with the curved faces 8 and 9 prevent the rim members 2 from slipping on the shoes or bearing members at the points 12 and the curved faces 8 react against the studs so as to enable the wheel to exert a good tractive effort upon the bearing memers. We prefer to employ a sufficient number of bearing members to insure that at least two of them will constantly lie substantially flat on the ground under the wheel. As the wheel passes from the rearmost bearing member onto the one forward, the spring or springs 10 attached to the rearmost bearing member pulls it upwardly so as to hold it in place on the wheel as the wheel rotates. We

prefer to form the underside of the plate bodies 6 of the shoes with depressions 13 which have the effect of increasing the biting power of the shoes on th ground. The

springs 10 are sufficiently strong to prevent the forward ends of the bearing members on the forward side of the wheel from becoming dislodged. As the bearing members descend on the forward side of the wheel,

the weight of each shoe exerts itself with a constantly increasing lever arm which results in slightly extending the springs, so that the bearing members swingoutwardly slightly at their forward portions and so asthough on a fulcrum about their heels or rear ends 14. In this way as the wheel rotates, it places the bearing members in succession substantially flatly upon the ground.

Under some circumstances, it may bedesirable to employ means on the bearing members for penetrating the earth. If this is desired, we prefer to employ spade-like members such as the traverse plate 15 indicated in dotted lines in Fig. 1. If these plates are used they are simply attached in slots on the plate bodies 6 of the bearing members.

The principle of. our invention may be apmember and the teeth like an ordinary rack and gear wheel and As further examples of applications of the invention reference is had to Figs. 3 and 4 which show two other distinct embodiments. In the form shown in Fig. 3 the bearing members are in the form of simple platr s 16 and while these plates constitute rack ec;

tions, the mechanical engagement between them and the wheel 17 is such as to employ a plurality of teeth instead of causing the shoe to operate as a single rack tooth. With this arrangement the teeth 18 of the bearing 19 of the wheel mesh these teeth keep the bearing'members from shiftingv on the wheel. Near the rear portions of the bearing members, springs 20 are attached which connect them with the wheel and pull them up into place on the wheel after the wheel has passed forward so as to roll onto the next bearing member. In this embodiment of the invention, as in the form shown in Fig. 1, the wheel may be actually supported by the contact of its rim 17 with the upper face of the plate and the teeth merely prevent slipping. 1

The embodiment shown in Fig. 4 is in some respects the reverse of that shown in the rim 24, so that the wheel rolls smoothly on the plate or bearing member 21 and exerts a tractive effort upon the rollers at the involute or cycloidal faces 25. Although in Fig. 1 we have shown the studs 5 as plain studs,,if desired, of course, these studs may be provided with rollers. y

The general problem which presents itself to this invention may be illustrated by referring to Figs. v5 and 6. In Fig. 5 we may regard the plate 26 as a short section of a continuous track along which the wheel 27 is to roll. As the wheel proceeds, the point 28 on the wheel comes in contact with the point 29 at the rear edge of the plate 26. As the wheel rolls off the plate the point 30 of the plate contacts with the forward edge of the plate at the point 31. The problem of the invention is not only to provide for this rolling effect but to prevent slipping of the rim of the wheel on this plate or bearing member.

In meeting the problem with a construction such as that illustrated in Fig. 1, the proper form for the forward and rear faces 8 and 9 of the bearing members may be plotted in-the manner illustrated in Fig. 6.

Referring to this figure, 32 represents the.

-arcs B B That is, the bearing member 21 is rim of the wheel which is supposed to be rolling upon the upper face 33 of the bearing'member. The point 34: represents the center of the wheel which is directly over the point of tangency 35 between the wheel and the bearing member. A succession of points, say for instance 10 points,, may be laid off toward the right on a horizontal line 36. These points are numbered a a etc. tea With these points as--. a center, we can locate the correspon ing positions of the stud or roller 37. The locus ofthe roller when so located is indicated by a suc- .cession of short arcs A A etc., corresponding. to the points a, a etc:, and if a curve is drawn tangent to these arcs, A, A, etc., it will give the proper outline or profile for the rear face of the bearing members. In a similar manner We may plot the curve for the forward face of the bearing members through the medium of a plurality of short etc. Corresponding to the points a a etc., we may lay 0H corresponding rim lines or arcs c c 0 etc., up to 0 In one aspect of the invention, the bearing members may be considered as constituting with the wheel a flexible rack which is continually passing under the wheel and upon which the Wheel rolls.

What We claim is:

1. In a tractor, the combination, with a Wheel, of a plurality of bearing members attached along the rim of the wheelfmcchanical engaging means between said bearing members and said wheel, consisting of guide members near the rim of the Wheel and engaging faces on said bearing meme bers, springs connecting said bearing members and said wheel and constructed to move an end of said members in a substan v tially radial direction, on said wheel the opposite end having limited gravity movement and each of said members having a substantially flat face on which the rim portions of said wheel ride.

2. In a tractor, the combination, with a Wheel, of a plurality of bearing members attached along the rim of the wheel, each bearing member consisting of a shoe constructed to engage the ground and having a curved forward face and a curved rear face so that each shoe constitutes an enlarged rack tooth, and springs holding said hearing members against said wheel and moving said members in a substantially radial direction on said wheel as said wheel. rolls over said bearing members.

3. In a tractor, the combmatlon of, a wheel having a plurality of rims, a plurality of bearing members disposed between said rims and bodily movable upon the wheel in and out in a substantially radial direction so that as the wheel advances it lays. said hearing members in. succession upon the ground,

springs attached to said wheel and to said ing slipping of the wheel on each bearing member. a

i. In a tractor, in combination, a wheel having two separated rim members, a plurality of equidistant engaging studs disposed in the space between said rim members, a plurality of shoes disposed respectively in the spaces between said studs, said shoes bodily movable in and out on the wheel in a substantially radial direction between said studs, springs attached to the wheel and exerting a tension on said shoes to pull the same inwardly. on the wheel, said wheel and said shoes operating. so that when the wheel advances it lays the shoes successively upon the ground 3nd rolls across the upper side of each shoe in succession, each shoe having a curved forward face designed to maintain engagement with its corresponding engaging stud to prevent the rim of the wheel slipping on the shoe and cooperating with the stud as a rack tooth. I

5. In a tractor, in combination, a wheel having two separated rim members, a plu-l r'ality of equidistant engaging studs carried thereby in the space between said rim members, a plurality of shoes disposed respectively in the spaces between said studs and bodily movable on the wheel and cooperating with said wheel so that when the wheel advances it lays the shoes successively upon the ground and rolls across the upper side of each shoe in succession, each shoe having a curved forward face operating to maintain engagement with its corresponding engaging stud to prevent the rim of the wheel slipping on the'shoe and cooperating with the stud as a rack tooth, and springs attached to said wheel and to the shoes respectively toward the rear part of each shoe, and exerting a tension on each shoe to pull each shoe inwardly on the wheel after the wheel has rolled over the sameand o crating to hold the shoes in place between t e studs.

6. In a tractor, the combination of a wheel, a plurality .of bearing memlbers attached around the rim of the wheel, and bodily n1ovable thereupon in and out in a substantially radial direction so that as the Wheel advances it lays said bearing members in succession upon the ground to enable the wheel to move forward by a rolling movement upon each bearing member, each bearing member consisting of a shoe constructed to rest upon the ground, having a curved forward face and a curved rear face so that each shoe constitutes a rack tooth, said wheel having means for engaging said curved faces, the said wheel operating as a gear wheel maintaining contact continuously with the faces of the shoe" as a gear tooth when it rolls upon the shoe, each shoe having concave faces of substantially the same radius as the rim of the wheel adjacent the side edges thereof, said wheel having rim portions rolling on said faces,

bearing member, said wheel and said bearing members having engaging faces maintaining contact continuously with each other during the rolling movement of the Wheel to prevent the wheel from slipping, and springs attached toward the rear ends of said bearing members with respect to the direction of rotation of the wheel for pulling the tractor members substantially radially inward on the wheel.

8. In a tractor, the combination, with a wheel, of a series of members carried on the rim of said wheel and having the shape of gear teeth, devices carried by said wheel between which said gear-tooth-shaped members ride, and springs holding said members in cbntact with said wheel rim and with said devices.

9. In a tractor, the combination, with a wheel, of a series of members carried on the rim of said wheel, but free to move bodily thereon andeach acting as a gear tooth, de vices fast on said wheel between which said members ride and against which the curved surfaces of said members roll, and springs holding said members ,on said wheel rim.

10. In a tractor, the combination, with awheel, of a series of members carried on the rim of said wheel and over which said wheel moves, said members having curved forward and rear surfaces and acting as gear teeth, devices fast on said Wheel adjacent said curved surfaces of said members, with which 'said curved surfaces coact, and means for yieldingly holding one end of said members in contact with said wheel rim and with said devices the opposite end being free to move by gravity within the limits determined by said devices.

n 11. In a tractor, the combination, with a wheel having oppositely disposed rims, of a series of members floating between guide members on said rims and over which said our hands in the presence of two subscribing wheel rolls, said members being bodlly movwltnesses.

able on said wheel and held in contact therewith solely 'by springs connected to said g S 5 wheel and said members, the opposite end being free to gravitate between limits deter- Witnesses:

mined by said guide members. L. R. ARROYO,

In testimony whereof we have herennto set Inc C. FUNK. 

